3D Printed Peristaltic Pump

PROJECT BY

Presented By:Frank Zhao

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ABOUT THIS PROJECT

Tell us briefly about your project. Is it a work of art or does it serve another
function?

This is a peristaltic pump, it is designed with emphasis on durability, and being ability to pump thick liquids at an easily controllable rate. It's purpose is to pump blended food into a person's feeding tube when they cannot physically eat.

When did you start working on this project and how long did it take you to complete?

I went to visit my grandfather, in China, when he had to start radiotherapy to treat his esophagus cancer. The first phase of the design was done on my aunt's tablet using Onshape (a cloud based equivalent to SolidWorks) on China’s 4G cell network while in the hospital. When I went back to the USA I did slightly more CAD work as I had a printer to do trial and error. 3D printing took 3 days, while the rest of the time was design, mechanical assembly, and circuitry. I finished the project and shipped it off to my family back in China exactly 2 weeks after I got back to the USA (June 2015).

What was your goal in building this project?

Feeding my grandfather is challenging because we were squeezing blended food through ordinary syringes. The feed rate must be slow to keep my grandfather comfortable (not feel bloated). We cannot rush and it also takes a lot of strength. I wanted to make this easier for everybody, as my aunts and uncles do not have unlimited days off, and I really don’t think grandmother has the strength to do this task alone.

Does your project help to solve a problem? If so what problem?

The pump makes it almost effortless to feed my grandfather, and it can be easily operated by my grandmother. It is relatively inexpensive compared to dedicated automated pumps. It is also much more reliable than cheaper “turkey baster” style pumps (which we tried and they all had problems and require even more strength, just less reloading required).
My grandfather himself was a doctor and a medic in the army. He absolutely refused to take the nutrient IVs that are typically used, this is why we were using blended food. He really wanted to keep his diet natural, and perhaps, keep his life as normal as possible, he eats what we eat, but blended.

What makes your idea unique?

The print is extra thick for durability, it is also printed at 100% infill. This presented thermodynamic challenges I had to solve, and also it takes over 24 hours to print just one of the piece. (I was originally planning on sending off designs to my local 3D hubs, to start the printing earlier, but 2 hubs straight up refused the job and one hub tried and it failed to print completely, turns out even 20 hours of reliable printing is impressive, my record so far is 60)
If you look at some other peristaltic pump designs, half of them won’t have an outer wall that the tube squeezes against. My design has a very thick wall, and this is how it can pump thick liquids. The wall and rollers can squeeze together to ensure that the liquid doesn’t flow backwards.
The motor is a gigantic motor with a gearbox that slows it down ridiculously, which also means it has a ridiculous amount of torque. I calculated about 25 pounds of torque at the radius of my rollers. I also designed and soldered a circuit to control this motor, which also involved writing firmware so that the speed and intervals of the motor can be controlled easily.
Side note: scientific or medical peristaltic pumps typically use stepper motors instead, because it is possible to control the flow down to millilitre accuracy. My pump is much cheaper and doesn’t need such accuracy, because my grandfather really only needs to “clear his plate”.
Link to my page describing my solution to the thermal shrink problem caused by printing at 100% infill: http://eleccelerator.com/prevent-corner-lifting-3d-printing-overkill-method/
Image of circuit: http://eleccelerator.com/pics/peristaltic_pump_circuit_pic.png , diagram linked below

In what capacity are you using bearings and what type of bearings?

There are 6 bearings, 2 bearings per roller. They are flanged, sealed, and stainless steel. Their job is to squeeze the liquid through the tubing in the peristaltic pump. These bearings are supported by stainless steel binding posts. Using bearings gives the pump extra durability.
I’ve seen plenty of designs with just 3D printed rollers, I didn’t feel those would be durable enough.

What is the most important thing you want people to know about your project?

Even a consumer desktop 3D printer can create incredibly useful and durable things.
If a certain design isn’t available yet, or if existing designs don’t fit your needs, then just design something from scratch by yourself.
All design files are available. The 3D models are available in original source format on my public Onshape account, you can edit it however you want. The circuit design and firmware are available on my website. Just like everything else I do, completely open source.
URL to Onshape 3D CAD model: https://cad.onshape.com/documents/21d93d7fa07f4e049c1e2344/w/f15984352f124ccf842135a6/e/a6b527154ccf435bbd13d291
Preview of CAD model: http://eleccelerator.com/pics/peristaltic_pump_cadpreview.png
Diagram of circuit: http://eleccelerator.com/pics/peristaltic_pump_circuit_diagram.png

How will you use the $5,000 prize?

Most probably: desktop CNC milling machine, laser cutter is a runner up option. My hand working skills are not as great as other people, so I typically rely on digital manufacturing to get precision and beauty in things I make.
My current work-in-progress projects are:
* a antweight combat robot, my first, and scheduled to enter RobotGames in April 2016
* a fully 3D printed Newtonian telescope, I have the parts printed already, I need to buy the expensive mirrors next
You can find my website at eleccelerator.com , and my username is frank26080115 on websites such as Instructables, Youtube, etc, where I share all my projects.